- ProQuest Statistical Insight
Indexes data from U.S. federal and state governments, universities, private associations and organizations, independent research groups, as well as international and intergovernmental organizations.
Statista collects data from a broad range of government and commercial sources. It's best for recent data.
- Social Explorer
Social Explorer is a detailed reference tool for current and historical Census data from 1790 to 2010. Data may be generated by browsing maps or building reports.
- ProQuest Statistical Abstract of the United States
Summary statistics for the US, collected from a variety of government agencies and companies.
- World DataBank
Contains over 500 timeseries indicators under the headings: world view, environment, economy, states and markets and global links. Data are at the country level only and are updated annually. Includes the World Development Indicators and Global Development Finance databases.
OECD.Stat includes data and metadata for OECD countries and selected non-member economies.
Topics include agriculture, development, economic projections, education, energy, environment, finance, and health.
- American FactFinder
Search data collected by the US Bureau of Census on housing, population, business and government.
- Human Development Reports
From the UN. Has data on key metrics of development.
- ICPSR: Inter-University Consortium for Political and Social Research
ICPSR maintains and provides access to a vast archive of social science data for research and includes many large time-series.
- World Population Prospects
Population projections from the United Nations Population Division. Projections now extend to 2100.
- Historical Statistics of the United States
Compilation of over 37,000 statistical series from over 1,000 sources. All tables include citations to data sources and descriptions of data anomalies. Each major section includes a signed essay that puts the statistics in historical context.